Process for producing formaldehyde and acetic acid



w. P. GE RG Filed Feb. 4, 1938 PROCESS FOR PRODUCING FORMALDEHYDE ANDAQETIC ACID a 7 kbfiwwwv a a A wh\hmu% $9 1 a, W I 7/ 1 i fiI 1' l M 3W7 k m n .r... mm 1 M x M W, o 1 c N a a 5 r0. 1 z m m W W. MM W w 6 maw in r 0 4 f. we m w, W 3 z N a .4 M a J mp. N V 1. y g WM 3, W m 6 a 2n 4 y 7 5 Z 2 1 2 M a a w T a m x y w? T 0 1. 1 7 444 a e u v, W 0 70 eJ H i 4M July 15, 1941.

vention.

Patented July 15, 1941,

UNITED STATES PATEN 2.24am raocsss roa raonucmo AND a r orriciz;

IORMALDEHYDE CETIO ACID William P. Gerg, Hancock, N. Y. ApplicationFebruary 4, 1988, Serial No. 188,756

This invention relates to a process for the production of formaldehydeand acetic acid.

A primary object of this invention is'the provision o: a process wherebysubstantially pure formaldehyde may be formed directly from methylacetate with a minimum of steps and operations.

A further object is the provision of a process whereby formaldehyde maybe produced from either methyl acetate. methyl alcohol or a mixture ofthe two.

An additional object is the provision of such a process of producingformaldehyde whereby acetic'acid may also be produced by the sameprocess and the resulting products, formaldehyde and acetic acid,recovered from methyl acetate or methyl alcohol or a mixture of the twosimultaneously.

An additional object is the provision of a process carrying out theabove objects wherein a relatively simple form of apparatus may beutilized requiring the use of a relatively small amount of heat andproducing a relatively'great yield of the products of the process with aminimum of steps.

any desired source and the admission thereof nese, aluminum, nickel,palladium, cerium sulphate and thorla, or oxides of any of the above.

or combinations of any two or more of them.

The catalyst may be in the form of a sponge,

a wire, a colloidal suspension or an impregnated sheet of any suitablesustaining material such The invention therefore, consists in the sequence of operations and certain novel steps comprising the processtogether with the combinations of ingredients utilised in conjunctiontherewith all as will be more fully pointed out hereinafter and shown inthe accompanying drawing wherein:

The single figure illustrates a diagrammatic representation of one formof apparatus suitable for carrying out the process of the instant in-Having reference now to the drawing there is indicated at is an inletpipe leading to a still or vaporizer H. Methyl acetate or methyl alcoho!or any desired mixture of the two is introduced into still H throughpipe I. where it is volatiiized by heat generated by steam which entersa coil it in still through a pipe I! and exits therefrom through a pipeN, or by any other desired heat producing means. The vapors of themixture then exit from still ii through a pipe l5, which contains aconstant pressure reducing valve H which may be manually orautomatically adjustable, to a pipe ll where air or oxygen in desirableproportions is introduced to the vapors of methyl acetate and/or methylalcohol. The vapors are mixed with the air or oxy en in any suitablemixing device i! and passed into a catalytic chamber 30. Air or oxygenis supplied to pipe" iron; 55

as pumice, asbestos or glass.

The catalytic reaction may be endothermic or exothermic and in the eventthat it is the-latter external heat may be supplied to catalytic chamber25 in any desired manner.

In the catalytic chamber the mixture of vapors of methyl acetate arid/ormethyl alcohol and air and/or omen are oxidized into'acetic acid,formaldehyde, methyl alcohol and inert gases. The latter mixture passesthrough a pipe 25 to a concentrating column 26. Concentrating orfractional distillation column 26 is heated in order to accelerate thedistillation of I the compounds contained therein by steam which passesthrough a pipe 2i into a coil 28 contained in the bottom of column 28and out of coil 28 through a pipe 29'. In the concentrating column theformaldehyde and inert are further volatilized and the acetic acidconcentrated. The concentrated acetic acid p through a pipe is into acondenser 3!, where it is liquefied and is drawn therefrom as through apipe 32 into any desired storage receptacle. The mixture of formaldehydeand inert gases and unconverted methyl acetate and,

methyl alcohol, however, passes upwardly through a pipe 35 to aformaldehyde absorption column 38 where the formaldehyde is dissolved bythe introduction of water, initially contained in a tank 81, which ispassed through'a pipe 3! controlled by a valve 3! into formaldehydeabsorption column 38. Thesolution ofiorm'aldehyde is thence drawnthrough a pipe it into a condenser 5i and withdrawn therefrom through,

a pipe 42 into any desired storage receptacle in the desired commercialform of a 40% formaldehyde solution in water. A return line 43 isprovided from the bottom of formaldehyde absorption column to a pointnear the top of concentrating column 26 to balance column 26 in a knownmanner.

Thus from the foregoing it will be seen that acetic acid andformaldehyde may readily be produced by the catalytic oxidation ofmethyl acetate and/or methyl alcohol with oxygen or air according to oneof the following reactions:

In the case of the third equation no acetic acid is produced since thereis no reaction doubling the carbon and that the oxidation is not carriedfar enough to produce acid.

The inert gases and unconverted methyl alcohol and methyl acetate whichpass into formaldehyde absorption column 3G with the formaldehyde arepassed therefrom through a pipe from tank 31 through a pipe 68 under thecon-' trol of a manual valve 51. The remaining inert gases, still ingaseous form pass from the top of column 55 through a pipe 80 whencethey may escape to the atmosphere or be recovered for any desiredpurpose.

The solution of methyl acetate removed'from the inert gases is passedthrough a pipe'fii to a concentrating column 62 supplied with steam orother heating medium through a pipe 63 leading to a coil iitwhich has anexit 65. Here the water is freed of methyl acetate and/or methyl alcoholand passed in liquid form out of column 62 as through a pipe 66. Thevaporized methyl acetate and/or methyl alcohol is passed out of column62 through a pipe 6'! to a condenser 58 whence it is passed through apipe 59 to a junction it with a pipe H which leads from gas separatingunit- 52 wherein it should here be pointed out a portion of the methylacetate and/or methyl alcohol is removed from the inert gases, and thecombined methyl acetate from pipes ii and 69 is returned through a pipeis to pipe Hi to be revolatilized in still H. A pipe 15 having a valve15a therein leads from the bottom of condenser 68 to a point adjacentthe top of concentrating column 62 to balance the column in a knownmanner.

Now from the foregoing it will be seen that there is herein provided animproved process for the production of formaldehyde and acetic acid frommethyl acetate or methyl alcohol or any mixture of the two in arelativelyinexpensive, simple and efficient manner.

Since many modifications may be made of the herein described process itis to be understood that all matter herein before set forth or shown inthe accompanying drawing is to be interpreted merely as illustrative andnot in a limiting therefrom with oxygen, oxidizing the resulting mixturein the presence of a vapor phase oxidation catalyst, the steps ofpassing the oxidized mixture including acetic acid and formaldehyde to aconcentrating column, concentrating the acetic acid drawing oil the sameand passingthe vaporized formaldehyde out of said column and separatingthe remaining methyl acetate from the formaldehyde.

2. The process for producing formaldehyde which comprises volatilizingmethyl acetate,- mixing the vapors therefrom with oxygen, oxidizing theresulting mixture in the presence of a vapor phase oxidation catalyst,the steps of passing the oxidized mixture of acetic acid, methylalcohol, vaporized methyl acetate, formaldehyde and inert gases to aconcentrating column separating acetic acid therefrom, passing theremaining mixture of formaldehyde, inert gases, methyl alcohol andmethyl acetate to a formaldehyde absorption column'forming a solution offormaldehyde and water, drawing off the said solution.

3. The process for producing formaldehyde which comprises volatilizingmethyl acetate, mixing the vapors therefrom with oxygen, oxidizing theresulting mixture in the presence of a vapor phase oxidation catalyst,the steps of passing the oxidized mixture of acetic acid, methylalcohol, vaporized methyl acetate, formaldehyde and inert gases to aconcentrating column, passing the mixture of formaldehyde, inert gases,methyl acetate to a formaldehyde absorption column, forming a solutionof formaldehyde and water, drawing off the said solution and separatingthe volatilized methyl acetate from the inert gases, condensing saidmethyl acetate and recycling the revolatilized mixture.

4. The process for simultaneously producing formaldehyde and acetic acidwhich comprises volatilizing methyl. acetate, mixing the vaporstherefrom with oxygen, oxidizing the resulting mixture in the presenceof a vapor phase oxidation catalyst, the steps of passing the oxidizedmixture of acetic acid, vaporized methyl acetate, formaldehyde and inertgases to a concentrating column, passing the mixture of formaldehyde,inert gases, methyl alcohol and methyl acetate to a formaldehydeabsorption column forming a solution of formaldehyde and water, anddrawing off the said solution.

WILLIAM P. GERG.

